Microporous Carbon and Carbon/Metal Composite Materials Derived from Bio-Benzoxazine-Linked Precursor for CO2 Capture and Energy Storage Applications

There is currently a pursuit of synthetic approaches for designing porous carbon materials with selective CO2 capture and/or excellent energy storage performance that significantly impacts the environment and the sustainable development of circular economy. In this study we prepared a new bio-based benzoxazine (AP-BZ) in high yield through Mannich condensation of apigenin, a naturally occurring phenol, with 4-bromoaniline and paraformaldehyde. We then prepared a PA-BZ porous organic polymer (POP) through Sonogashira coupling of AP-BZ with 1,3,6,8-tetraethynylpyrene (P-T) in the presence of Pd(PPh3)4. In situ Fourier transform infrared spectroscopy and differential scanning calorimetry revealed details of the thermal polymerization of the oxazine rings in the AP-BZ monomer and in the PA-BZ POP. Next, we prepared a microporous carbon/metal composite (PCMC) in three steps: Sonogashira coupling of AP-BZ with P-T in the presence of a zeolitic imidazolate framework (ZIF-67) as a directing hard template, affording a PA-BZ POP/ZIF-67 composite; etching in acetic acid; and pyrolysis of the resulting PA-BZ POP/metal composite at 500 °C. Powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller (BET) measurements revealed the properties of the as-prepared PCMC. The PCMC material exhibited outstanding thermal stability (Td10 = 660 °C and char yield = 75 wt%), a high BET surface area (1110 m2 g–1), high CO2 adsorption (5.40 mmol g–1 at 273 K), excellent capacitance (735 F g–1), and a capacitance retention of up to 95% after 2000 galvanostatic charge–discharge (GCD) cycles; these characteristics were excellent when compared with those of the corresponding microporous carbon (MPC) prepared through pyrolysis of the PA-BZ POP precursors with a ZIF-67 template at 500 °C.


Introduction
Benzoxazine (BZ) is a six-membered heterocyclic molecule, containing oxygen and nitrogen atoms, that is stable at room temperature or in humid environments; BZ derivatives are readily prepared through Mannich condensations of phenol derivatives with paraformaldehyde and primary amines in the melt or in solution [1][2][3][4][5]. Ring-opening 2 of 19 polymerization (ROP) of the oxazine ring in a BZ precursor can be performed by applied heat, without adding any catalyst or initiator, to afford a polybenzoxazine (PBZ) as a thermosetting polymeric material [1][2][3][4][5]. PBZs are interesting materials in the industry and academia because of their excellent dimensional stability, low dielectric constants, high thermal stability, excellent adhesive strength, catalyst-free polymerization, light weight, good mechanical properties, high glass transition temperatures (T g ), low surface free energies, good electrical properties, smart macromolecular design flexibility, near-zero volumetric expansion, high char yield, and rapid improvement in physical and mechanical properties at low conversion, making them useful alternatives to compared to traditional thermosetting resins (e.g., phenolic, polyimide, epoxy, bismaleimides) [6][7][8][9].
Taking advantage of the unique properties of BZs, POPs, and metal-organic frameworks, in this study we prepared porous carbons-a microporous carbon (MPC) and a microporous carbon/metal composite (PCMC)-and examined their properties and potential applications. We synthesized a new bio-based BZ (AP-BZ) through Mannich condensation of apigenin and then prepared a PA-BZ POP through Sonogashira coupling of AP-BZ with 1,3,6,8-tetraethynylpyrene (P-T) (Scheme 1). We used differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy to investigate the thermal stability and ROP of both AP-BZ and PA-BZ POP. Next, we used a zeolitic imidazolate framework (ZIF-67) as a directing template to prepare a PA-BZ POP/ZIF-67 composite; after removing the core of ZIF-67 through etching in acetic acid and pyrolyzing at 500 • C, we obtained a PCMC exhibiting outstanding thermal stability, a high Brunauer-Emmett-Teller (BET) surface area, high CO 2 adsorption, and excellent supercapacitance, when compared with those of the corresponding MPC prepared through pyrolysis of the PA-BZ POP precursors at 500 • C. heteroatoms and/or redox moieties, thereby providing the chance to merge the features of both pseudocapacitor and EDLC mechanisms [43][44][45][46][47].
Taking advantage of the unique properties of BZs, POPs, and metal-organic frameworks, in this study we prepared porous carbons-a microporous carbon (MPC) and a microporous carbon/metal composite (PCMC)-and examined their properties and potential applications. We synthesized a new bio-based BZ (AP-BZ) through Mannich condensation of apigenin and then prepared a PA-BZ POP through Sonogashira coupling of AP-BZ with 1,3,6,8-tetraethynylpyrene (P-T) (Scheme 1). We used differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy to investigate the thermal stability and ROP of both AP-BZ and PA-BZ POP. Next, we used a zeolitic imidazolate framework (ZIF-67) as a directing template to prepare a PA-BZ POP/ZIF-67 composite; after removing the core of ZIF-67 through etching in acetic acid and pyrolyzing at 500 °C, we obtained a PCMC exhibiting outstanding thermal stability, a high Brunauer-Emmett-Teller (BET) surface area, high CO2 adsorption, and excellent supercapacitance, when compared with those of the corresponding MPC prepared through pyrolysis of the PA-BZ POP precursors at 500 °C.

Synthesis and Characterization of AP-BZ Monomer
Scheme 1 presents our synthetic approach toward the new bio-based BZ (AP-BZ) (Scheme 1b) based on apigenin, containing a free phenolic OH group, through the one-Scheme 1. Synthesis of (b) AP-BZ and (c) PA-BZ POP precursors from (a) apigenin.

Synthesis and Characterization of AP-BZ Monomer
Scheme 1 presents our synthetic approach toward the new bio-based BZ (AP-BZ) (Scheme 1b) based on apigenin, containing a free phenolic OH group, through the one-pot reaction of apigenin (as the phenol) with 4-bromoaniline and paraformaldehyde in 1,4dioxane and absolute EtOH at 90 • C for 24 h. When we attempted to prepare AP-BZ using pot reaction of apigenin (as the phenol) with 4-bromoaniline and paraformaldehyde in 1,4-dioxane and absolute EtOH at 90 °C for 24 h. When we attempted to prepare AP-BZ using DMSO as the solvent, the resulting product contained a lot of impurities and was very difficult to purify. Therefore, we performed the reaction in 1,4-dioxane and absolute EtOH as co-solvents to improve the solubility of apigenin. FTIR and NMR spectra confirmed the successful synthesis of AP-BZ. The FTIR spectrum of AP-BZ ( Figure S1) featured absorption bands centered at 3380, 3025, 1668, 1581, 1500, 1240, and 940 cm -1 , which we assign to the free phenolic OH group, the aromatic C-H unit, the C=O group, the C=C unit of the benzopyrone structure, the C=C unit in the apigenin structure, C-O-C antisymmetric stretching of the oxazine structure, and a BZ-related band, respectively. Figure 1 present the 1 H and 13 C NMR spectra of apigenin and AP-BZ in DMSO-d6, recorded at 25 °C. The 1 H NMR spectrum of apigenin ( Figure 1a) featured signals at 12.94 and 7.88-6.20 ppm, representing the phenolic OH group and aromatic protons, respectively; the 1 H NMR spectrum of AP-BZ (Figure 1b) featured signals at 12.94, 7.97-6.63, 5.61, and 4.82 ppm, assigned to the protons of the free OH group, the aromatic ring, and the OCH2N and ArCH2O units, respectively. The 13 C NMR spectrum of apigenin ( Figure 1c) featured peaks at 182.62, 161.99, and 103.43 ppm, representing the carbon nuclei of the C=O group and benzopyrone unit. The presence of an oxazine ring in AP-BZ was confirmed through its 13 C NMR spectrum (Figure 1d), which featured signals for carbon nuclei at 183.13, 80.08, and 44.79 ppm representing the C=O group and OCH2N and ArCH2O units, respectively. The FTIR and NMR spectral data confirmed the synthesis of AP-BZ (with a yield of 85%) and that its structure contained apigenin and oxazine units.  Next, were used DSC and in situ FTIR spectroscopy ( Figure 2) to investigate the thermal ROP of the oxazine ring in the AP-BZ monomer. The DSC profile of the uncured AP-BZ ( Figure 2a) revealed two types of thermal events: a sharp endothermic peak at 185 °C, due to the melting of AP-BZ, indicating its high purity, and a thermal event at 229 °C that we attribute to complete ROP of the oxazine ring in the AP-BZ structure. As reported previously, BZ monomers containing free phenolic OH groups can act as efficient catalysts Next, were used DSC and in situ FTIR spectroscopy ( Figure 2) to investigate the thermal ROP of the oxazine ring in the AP-BZ monomer. The DSC profile of the uncured AP-BZ ( Figure 2a) revealed two types of thermal events: a sharp endothermic peak at 185 • C, due to the melting of AP-BZ, indicating its high purity, and a thermal event at 229 • C that we attribute to complete ROP of the oxazine ring in the AP-BZ structure. As reported previously, BZ monomers containing free phenolic OH groups can act as efficient catalysts that lower the exothermic curing temperature of the oxazine ring, relative to that of traditional BZ resins [54,55]. Notably, the polymerization temperature of AP-BZ was very low when compared with those of the traditional BZ monomers TPE-BZ and TPEP-BZ [52], due the acidic character of the phenolic OH group in AP-BZ accelerating the polymerization of the oxazine ring, consistent with previous studies [26]. Interestingly, after thermal curing polymerization of AP-BZ at 110 and 150 • C, the DSC profiles featured the endothermic peak of the AP-BZ monomer at 186 • C, indicating the stability of the crystalline properties of AP-BZ at these two temperatures. The maximum exothermic peak of AP-BZ monomer cured at these two temperatures had shifted to 220 and 221 • C, respectively. When we increased the thermal treatment temperature to 180 • C, the intensity of the exothermic curing peak of AP-BZ decreased, then disappearing completely when cured at 210 and 250 • C, indicating the complete curing polymerization of the oxazine ring in AP-BZ to form poly(AP-BZ) (Scheme S1). We used in situ FTIR spectroscopy to examine the thermal polymerization behavior of AP-BZ at the various temperatures ( Figure 2b). As mentioned above ( Figure S1 and Figure 2b), the spectrum of the uncured AP-BZ featured characteristic absorption bands for the C=O group, the C=C stretching vibration of the benzopyrone structure, C-O-C antisymmetric stretching of the oxazine ring, and a BZrelated vibration at 1581, 1500, 1240, and 940 cm -1 , respectively. The bands at 1240 and 940 cm -1 representing the C-O-C antisymmetric stretching of the oxazine ring and the BZ-related vibration, respectively, remained in the FTIR spectra recorded after thermal treatment at 110 and 150 • C, but had decreased in intensity and ultimately disappeared completely when treated at 180, 210, and 250 • C, indicating that ROP of the oxazine ring in AP-BZ had occurred at these latter temperatures to form poly(AP-BZ). The DSC data were consistent with those from the FTIR spectral analyses. that lower the exothermic curing temperature of the oxazine ring, relative to that of traditional BZ resins [54,55]. Notably, the polymerization temperature of AP-BZ was very low when compared with those of the traditional BZ monomers TPE-BZ and TPEP-BZ [52], due the acidic character of the phenolic OH group in AP-BZ accelerating the polymerization of the oxazine ring, consistent with previous studies [26]. Interestingly, after thermal curing polymerization of AP-BZ at 110 and 150 °C, the DSC profiles featured the endothermic peak of the AP-BZ monomer at 186 °C, indicating the stability of the crystalline properties of AP-BZ at these two temperatures. The maximum exothermic peak of AP-BZ monomer cured at these two temperatures had shifted to 220 and 221 °C, respectively. When we increased the thermal treatment temperature to 180 °C, the intensity of the exothermic curing peak of AP-BZ decreased, then disappearing completely when cured at 210 and 250 °C, indicating the complete curing polymerization of the oxazine ring in AP-BZ to form poly(AP-BZ) (Scheme S1). We used in situ FTIR spectroscopy to examine the thermal polymerization behavior of AP-BZ at the various temperatures ( Figure 2b). As mentioned above (Figures S1 and 2b), the spectrum of the uncured AP-BZ featured characteristic absorption bands for the C=O group, the C=C stretching vibration of the benzopyrone structure, C-O-C antisymmetric stretching of the oxazine ring, and a BZ-related vibration at 1581, 1500, 1240, and 940 cm -1 , respectively. The bands at 1240 and 940 cm -1 representing the C-O-C antisymmetric stretching of the oxazine ring and the BZ-related vibration, respectively, remained in the FTIR spectra recorded after thermal treatment at 110 and 150 °C, but had decreased in intensity and ultimately disappeared completely when treated at 180, 210, and 250 °C, indicating that ROP of the oxazine ring in AP-BZ had occurred at these latter temperatures to form poly(AP-BZ). The DSC data were consistent with those from the FTIR spectral analyses. We applied both the Kissinger and Ozawa equations to evaluate the activation energy (Ea) of the AP-BZ monomer from the DSC data measured at the various heating rates ( Figure S2a-c). Based on the Kissinger and Ozawa methods [56,57], we calculated values of Ea for the AP-BZ monomer of 23.93 and 8.36 kJ mol -1 , respectively, suggesting low-energy activation of the polymerization of AP-BZ. Notably, our new AP-BZ displayed values of Ea much lower than those of other BZ monomers, bis-BZ monomers, We applied both the Kissinger and Ozawa equations to evaluate the activation energy (E a ) of the AP-BZ monomer from the DSC data measured at the various heating rates ( Figure S2a-c). Based on the Kissinger and Ozawa methods [56,57], we calculated values of E a for the AP-BZ monomer of 23.93 and 8.36 kJ mol -1 , respectively, suggesting low-energy activation of the polymerization of AP-BZ. Notably, our new AP-BZ displayed values of E a much lower than those of other BZ monomers, bis-BZ monomers, and a previously prepared apigenin-based BZ (API-fa) [25,26]. This unique characteristic of AP-BZ during polymerization inspired us to prepare POP derivatives for application to energy storage and gas capture. To examine the thermal stability of the uncured AP-BZ and of AP-BZ after thermal treatment (at 110, 150, 180, 210, and 250 • C for 2 h each temperature), we performed TGA analyses under a N 2 atmosphere at a heating rate of 20 • C min -1 ( Figure 3). We used the values of T d5 and T d10 and the char yield at 800 • C to characterize the thermal stability of the uncured and the cured AP-BZ samples. Figure 3 reveals that the values of T d5 and T d10 and the char yield of the uncured AP-BZ were 237 and 280 • C and 14 wt%, respectively. As expected, both the thermal degradation temperatures and the char yield of AP-BZ increased significantly upon increasing the thermal curing temperature from 110 to 250 • C, due to the formation of crosslinked structures with increasing crosslinking density after ROP of the oxazine ring. The poly(AP-BZ) obtained after thermal curing at 250 • C had higher thermal stability-characterized by higher values of T d5 (340 • C) and T d10 (382 • C) and a higher char yield (45 wt %)-than the previously reported BZ monomers poly(AP-f), poly(BA-a), and poly(NAR-fa) [25,26]. and a previously prepared apigenin-based BZ (API-fa) [25,26]. This unique characteristic of AP-BZ during polymerization inspired us to prepare POP derivatives for application to energy storage and gas capture. To examine the thermal stability of the uncured AP-BZ and of AP-BZ after thermal treatment (at 110, 150, 180, 210, and 250 °C for 2 h each temperature), we performed TGA analyses under a N2 atmosphere at a heating rate of 20 °C min -1 ( Figure 3). We used the values of Td5 and Td10 and the char yield at 800 °C to characterize the thermal stability of the uncured and the cured AP-BZ samples. Figure 3 reveals that the values of Td5 and Td10 and the char yield of the uncured AP-BZ were 237 and 280 °C and 14 wt%, respectively. As expected, both the thermal degradation temperatures and the char yield of AP-BZ increased significantly upon increasing the thermal curing temperature from 110 to 250 °C, due to the formation of crosslinked structures with increasing crosslinking density after ROP of the oxazine ring. The poly(AP-BZ) obtained after thermal curing at 250 °C had higher thermal stabilitycharacterized by higher values of Td5 (340 °C) and Td10 (382 °C) and a higher char yield (45 wt %)-than the previously reported BZ monomers poly(AP-f), poly(BA-a), and poly(NAR-fa) [25,26].

Synthesis and Characterization of PA-BZ POP
Scheme 1c present the preparation of the PA-BZ POP through Sonogashira coupling of AP-BZ with P-T in the presence of a Pd catalyst in DMF/Et3N at 90 °C for 72 h. FTIR and 13 C NMR solid state spectroscopy confirmed its successful synthesis. The FTIR spectrum of AP-BZ (Figure 4a), recorded at 25 °C, featured absorption bands at 3423 cm -1 for the phenolic OH group, 3054 cm -1 for the aromatic C-H units, 2192 cm -1 for internal and terminal -C≡C-stretching, 1645 cm -1 for the C=O groups, and 941 cm -1 for the BZrelated vibration. The solid state 13

Synthesis and Characterization of PA-BZ POP
Scheme 1c present the preparation of the PA-BZ POP through Sonogashira coupling of AP-BZ with P-T in the presence of a Pd catalyst in DMF/Et 3 N at 90 • C for 72 h. FTIR and 13 C NMR solid state spectroscopy confirmed its successful synthesis. The FTIR spectrum of AP-BZ (Figure 4a), recorded at 25 • C, featured absorption bands at 3423 cm -1 for the phenolic OH group, 3054 cm -1 for the aromatic C-H units, 2192 cm -1 for internal and terminal -C≡C-stretching, 1645 cm -1 for the C=O groups, and 941 cm -1 for the BZ-related vibration. The solid state 13 C CP/MAS NMR spectral profile of AP-BZ POP (Figure 4b) displayed six major peaks for the carbon nuclei in AP-BZ: at 180.27 ppm for the C=O group, 164.40 ppm for the C=C unit in the benzopyrone structure of apigenin, 128.93-103.92 ppm for the aromatic units, and 80.98-67.14 ppm for the alkyne units. Signals for the carbon nuclei of AP-BZ POP appeared at 80.98 ppm for the OCH 2 N unit and at 46.79 ppm for the ArCH 2 N unit, confirming the presence of oxazine rings. Furthermore, the maximum exothermic curing peak of the oxazine ring of the AP-BZ POP appeared at 257 • C in the DSC thermograms Figure 4c). The semicrystalline character of the PA-BZ POP was evidenced by three major diffraction peaks appearing at 10.18, 20.79, and 40.79 • in the X-ray diffraction (XRD) pattern as presented in Figure 4d [12,45,58]. We also investigated the ROP of PA-BZ POP through in situ FTIR spectroscopic analyses at temperatures from 25 to 250 • C ( Figure S3). The absorption bands at 1232 and 921 cm -1 for the BZ ring disappeared completely after thermal curing polymerization at temperatures of 210 and 250 • C, consistent with the formation of poly(PA-BZ POP) and complete opening of the oxazine ring at these curing temperatures. Scheme S2 presents a possible structure of poly(PA-BZ POP) after ROP. SEM and TEM images ( Figure S4a-d) revealed irregular spherical porous and microporous structures for the surface morphologies of the PA-BZ POP. The BET surface area of the PA-BZ POP was low (25 m 2 g -1 ), as calculated from N 2 adsorption/desorption measurements. ppm for the ArCH2N unit, confirming the presence of oxazine rings. Furthermore, the maximum exothermic curing peak of the oxazine ring of the AP-BZ POP appeared at 257 °C in the DSC thermograms Figure 4c). The semicrystalline character of the PA-BZ POP was evidenced by three major diffraction peaks appearing at 10.18, 20.79, and 40.79° in the X-ray diffraction (XRD) pattern as presented in Figure 4d [12,45,58]. We also investigated the ROP of PA-BZ POP through in situ FTIR spectroscopic analyses at temperatures from 25 to 250 °C ( Figure S3). The absorption bands at 1232 and 921 cm -1 for the BZ ring disappeared completely after thermal curing polymerization at temperatures of 210 and 250 °C, consistent with the formation of poly(PA-BZ POP) and complete opening of the oxazine ring at these curing temperatures. Scheme S2 presents a possible structure of poly(PA-BZ POP) after ROP. SEM and TEM images ( Figure S4a-d) revealed irregular spherical porous and microporous structures for the surface morphologies of the PA-BZ POP. The BET surface area of the PA-BZ POP was low (25 m 2 g -1 ), as calculated from N2 adsorption/desorption measurements.

Formation of PCMC
Scheme 2 outlines the preparation of the PCMC. In the first step, in situ polymerization of AP-BZ and P-T through Sonogashira coupling in the presence of ZIF-67 as a director template, Pd(PPh 3 ) 4 as the catalysts, and a mixture of DMF/Et 3 N as the solvent afforded PA-BZ POP/ZIF-67 composites (Scheme 2a). Next, the PA-BZ POP/ZIF-67 composites were immersed and stirred in acetic acid for 24 h at room temperature to remove the core ZIF-76 and provide a PA-BZ POP/metal composite (Scheme 2b). Finally, the as-prepared PA-BZ POP/metal composite was carbonized by heating at a rate of 5 • C min -1 up to 500 • C and then maintaining that temperature for 8 h, giving the PCMC as a black solid (Scheme 2c).

Formation of PCMC
Scheme 2 outlines the preparation of the PCMC. In the first step, in situ polymerization of AP-BZ and P-T through Sonogashira coupling in the presence of ZIF-67 as a director template, Pd(PPh3)4 as the catalysts, and a mixture of DMF/Et3N as the solvent afforded PA-BZ POP/ZIF-67 composites (Scheme 2a). Next, the PA-BZ POP/ZIF-67 composites were immersed and stirred in acetic acid for 24 h at room temperature to remove the core ZIF-76 and provide a PA-BZ POP/metal composite (Scheme 2b). Finally, the as-prepared PA-BZ POP/metal composite was carbonized by heating at a rate of 5 °C min -1 up to 500 °C and then maintaining that temperature for 8 h, giving the PCMC as a black solid (Scheme 2c). This new PCMC material was characterized through XRD, TGA, and BET measurements. Figure 5 [61][62][63][64][65]. Finally, we examined the thermal stabilities of these six samples through TGA under a N2 atmosphere ( Figure 6). The values of Td5 and Td10 and the char yield of PA-BZ-POP were 198 °C, 311 °C, and 57.7 wt%, respectively; for ZIF-67, they were 293 °C, 407 °C, and 35.1 wt%, respectively; for the PA-BZ POP/ZIF-67 composite they were 278 °C, 398 °C, and 55.2 wt%, respectively; for the PA-BZ POP/metal composite they were 275 °C, 382 °C, and 55.7 wt% respectively; for the MPC they were 513 °C, 583 °C, and 70.9 wt%, respectively; and for the PCMC they were 532 °C, 660 °C, and 75.0 wt%, respectively. The TGA data presented two interesting phenomena: First, the thermal stabilities of PA-BZ POP/ZIF-67 and PA-BZ POP/metal composite were outstanding when compared with that of the pure PA-BZ POP, due to the presence of ZIF-67 and the formation of a composite after removing the ZIF-67 framework. Second, the thermal degradation temperature and char yield of the PCMC were higher than those of the MPC, presumably because the former This new PCMC material was characterized through XRD, TGA, and BET measurements. Figure 5 presents the XRD patterns of PA-BZ POP, ZIF-67, PA-BZ POP/ZIF-67, PA-BZ POP/metal composite, MPC, and PCMC, each recorded at room temperature. As mentioned earlier, the PA-BZ POP had semicrystalline character (Figures 4d and 5a). The  [61][62][63][64][65]. Finally, we examined the thermal stabilities of these six samples through TGA under a N 2 atmosphere ( Figure 6). The values of T d5 and T d10 and the char yield of PA-BZ-POP were 198 • C, 311 • C, and 57.7 wt%, respectively; for ZIF-67, they were 293 • C, 407 • C, and 35.1 wt%, respectively; for the PA-BZ POP/ZIF-67 composite they were 278 • C, 398 • C, and 55.2 wt%, respectively; for the PA-BZ POP/metal composite they were 275 • C, 382 • C, and 55.7 wt% respectively; for the MPC they were 513 • C, 583 • C, and 70.9 wt%, respectively; and for the PCMC they were 532 • C, 660 • C, and 75.0 wt%, respectively. The TGA data presented two interesting phenomena: First, the thermal stabilities of PA-BZ POP/ZIF-67 and PA-BZ POP/metal composite were outstanding when compared with that of the pure PA-BZ POP, due to the presence of ZIF-67 and the formation of a composite after removing the ZIF-67 framework. Second, the thermal degradation temperature and char yield of the PCMC were higher than those of the MPC, presumably because the former had a nanoparticle-embedded porous carbon structure that improved the thermal stability of this material.  The porosities and pore size diameter of MPC, ZIF-67, and PCMC materials were identified using N2 sorption isotherms (Figure 7). The pure MPC material provided a type   The porosities and pore size diameter of MPC, ZIF-67, and PCMC materials were identified using N2 sorption isotherms (Figure 7). The pure MPC material provided a typ The porosities and pore size diameter of MPC, ZIF-67, and PCMC materials were identified using N 2 sorption isotherms (Figure 7). The pure MPC material provided a type I isotherm with an upsurge in the N 2 absorption curve occurring at a value of P/P 0 of less than 0.10, and only a slight upsurge in the range 0.1-1 (Figure 7a). The ZIF-67 template (Figure 7b) also exhibited a type I isotherm, with very large upsurge in the N 2 absorption curve at a value of P/P 0 of less than 0.10, a slight upsurge in the range 0.03-0.85, and finally another upsurge in the range 0.85-1. In contrast, the PCMC (Figure 7c) provided a type IV isotherm, with an upsurge in the N 2 absorption curve at a value of P/P 0 of less than 0.10, a slight upsurge in the range 0.03-0.49, and finally a narrow hysteresis loop in the range 0.49-1, suggesting the presence of micropores and mesopores inside this material. The BET surface areas were 403 m 2 g -1 for MPC and 930 m 2 g -1 for ZIF-67; the PCMC possessed the highest BET surface area (1110 m 2 g -1 ), presumably because of the growth of ZIF-67 particles inside the pores of the PA-BZ POP material, and after removing the ZIF-67 via etching process and after further activation at 500 • C dramatically improved the porosity and surface area [51]. I isotherm with an upsurge in the N2 absorption curve occurring at a value of P/P0 of less than 0.10, and only a slight upsurge in the range 0.1-1 (Figure 7a). The ZIF-67 template (Figure 7b) also exhibited a type I isotherm, with very large upsurge in the N2 absorption curve at a value of P/P0 of less than 0.10, a slight upsurge in the range 0.03-0.85, and finally another upsurge in the range 0.85-1. In contrast, the PCMC (Figure 7c)  Because of the high BET surface areas and thermal stabilities of the MPC and PCMC, we expected that these materials could be applied for CO2 adsorption and energy storage. We performed CO2 uptake measurements for the MPC and PCMC at 273 and 298 K, respectively (Figure 8). The amount of CO2 captured by the MPC and PCMC were 3.01 Because of the high BET surface areas and thermal stabilities of the MPC and PCMC, we expected that these materials could be applied for CO 2 adsorption and energy storage. We performed CO 2 uptake measurements for the MPC and PCMC at 273 and 298 K, respectively ( Figure 8). The amount of CO 2 captured by the MPC and PCMC were 3.01 and 3.30 mmol g -1 , respectively, at 298 K (Figure 8a) and 4.96 and 5.40 mmol g -1 , respectively, at 273 K (Figure 8b). We attribute the higher CO 2 uptake for PCMC to its higher surface area (1110 m 2 g -1 ) and abundance of micropores that provided suitable spaces for CO 2 uptake. Furthermore, because of its high surface area and large pores, the CO 2 adsorption of our PCMC was excellent when compared with that of other previously reported porous materials, including poly(TPE-TPE-BZ), poly(Py-TPE-BZ), BPOP-1, the BZ-linked material BoxPOP-1, the ferrocene-containing material Fc-CMP-1, A6CMP-3, CTF-HUST-3, the triphenylamine-based polymer PTPA-3, CTHP-3, and COF-102 [66][67][68][69][70][71][72][73][74].

Electrochemical Performance
We examined the electrochemical performance of our samples through voltammetry (CV) and galvanostatic charge/discharge (GCD) measurements in electrode system in 1 M aqueous KOH. Figure 9a-d display the CV curves of our s recorded at various sweep rates from 5 to 200 mV s -1 in the potential window from 0.90 V (vs. Hg/HgO). The CV curves of all samples were rectangular in shape, eve recorded at the highest scan rate of 200 mV s -1 , implying that the capacitive r originated mainly from EDLC, with minor pseudocapacitance. The pseudocap arose from the presence of various types of oxygen and nitrogen species. The int area of the PA-BZ POP sample was higher than those of the other samples, reve superior electrochemical performance. Furthermore, the current density increase increasing the sweep rate, while retaining the shapes of these CV curves, suggestio kinetics and good rate capability [45,46,75].

Electrochemical Performance
We examined the electrochemical performance of our samples through cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) measurements in a three-electrode system in 1 M aqueous KOH. Figure 9a-d display the CV curves of our samples, recorded at various sweep rates from 5 to 200 mV s -1 in the potential window from 0.10 to 0.90 V (vs. Hg/HgO). The CV curves of all samples were rectangular in shape, even when recorded at the highest scan rate of 200 mV s -1 , implying that the capacitive response originated mainly from EDLC, with minor pseudocapacitance. The pseudocapacitance arose from the presence of various types of oxygen and nitrogen species. The integrated area of the PA-BZ POP sample was higher than those of the other samples, revealing its superior electrochemical performance. Furthermore, the current density increased upon increasing the sweep rate, while retaining the shapes of these CV curves, suggestion facile kinetics and good rate capability [45,46,75]. Figures 10a-d present the GCD curves of our samples, determined at various current densities. The GCD curves of all of the samples were triangular in shape, with only a slight bend, indicating both EDLC and pseudocapacitive characteristics [45,46]. After calcination at 500 °C, the discharging times of both the MPC and PCMC samples were longer than those of the PA-BZ POP and PA-BZ POP/metal composite (Figure 10a-d), indicating that calcination had an enhancement effect on the capacitance of our MPC and PCMC.  Figure 11a displays the specific capacitances of all of the samples, determined from GCD curves using Equation (S1). The capacitance of the PCMC was excellent (735 F g -1 ) and highest among the tested samples (PA-BZ POP: 331 F g -1 ; PA-BZ POP/metal   [45,46]. After calcination at 500 • C, the discharging times of both the MPC and PCMC samples were longer than those of the PA-BZ POP and PA-BZ POP/metal composite (Figure 10a-d Figures 10a-d present the GCD curves of our samples, determined at various current densities. The GCD curves of all of the samples were triangular in shape, with only a slight bend, indicating both EDLC and pseudocapacitive characteristics [45,46]. After calcination at 500 °C, the discharging times of both the MPC and PCMC samples were longer than those of the PA-BZ POP and PA-BZ POP/metal composite (Figure 10a-d Figure 11a displays the specific capacitances of all of the samples, determined from GCD curves using Equation (S1). The capacitance of the PCMC was excellent (735 F g -1 ) and highest among the tested samples (PA-BZ POP: 331 F g -1 ; PA-BZ POP/metal  Figure 11a displays the specific capacitances of all of the samples, determined from GCD curves using Equation (S1). The capacitance of the PCMC was excellent (735 F g -1 ) and highest among the tested samples (PA-BZ POP: 331 F g -1 ; PA-BZ POP/metal composite: 274 F g -1 ; PCM: 349 F g -1 ) at a current density of 0.5 A g -1 . This behavior can be explained in terms of a higher surface area (1113 m 2 g -1 ), the existence of microporosity (average pore size: 1.5 nm), and the presence of various types of nitrogen and oxygen heteroatoms (primarily pyridinic N species; C=O and phenolic OH groups), thereby enabling ready access of electrolytes to the electrode surface [45,46]. In addition, the capacitance of the PCMC was excellent when compared with those of other porous materials (Table S1). Furthermore, upon increasing the current density from 0.5 to 20 A g -1 , the specific capacitances of all of the CMP samples decreased, due to there being insufficient time for ionic diffusion and adsorption inside the smallest pores within the large particles at high current densities [45,46]. We tested the durability of all of our samples through GCD measurements performed over 2000 cycles at a current density of 10 A g -1 (Figure 11b). The PA-BZ POP, PA-BZ POP/metal composite, MCP, and PCMC samples displayed good cycling stability, with 87.5, 88.6, 91.0, and 95.0% retention, respectively, of their original capacitances after 2000 cycles, indicating excellent cycling stability in 1 M KOH as the electrolyte. Recently, we prepared ferrocene-derived conjugated microporous polymers (FFC-CMPs) and then formed an inclusion complex with a BZ-linked β-cyclodextrin (Py-FFC-CMP/CD-BZ) [12]; this material exhibited capacitance of only 46 F g -1 at 0.5 A g -1 . In addition, we have previously prepared a series of CMPs through Sonogashira-Hagihara cross-couplings of a tetrabenzonaphthalene (TBN) monomer with tetraphenylethylene (TPE), pyrene (Py), and carbazole (Car) units; we then mixed them with highly conductive single-walled carbon nanotubes (SWCNTs) to improve their conductivity [45], with the TBN-Py-CMP/SWCNT composite exhibiting high capacitance (430 F g -1 ) at a current density of 0.5 A g -1 because of strong π-stacking of the SWCNTs with the CMPs [45]. In addition, we have previously prepared two-hybrid porous POSS-F-POIP and POSS-A-POIP materials through Heck reactions of octavinylsilsesquioxane (OVS) with brominated fluorene (F-Br 2 ) and anthraquinone (A-Br 2 ) derivatives, respectively [47]. These POSS-A-POIP and POSS-F-POIP materials exhibited specific capacitances of 152.5 and 36.2 F g -1 , respectively, at 0.5 A g -1 .
The higher capacitance of POSS-A-POIP was due to the faradaic reaction of anthraquinone and the π-conjugated system [47]. Shao et al. [76] prepared N-doped Cobalt@graphitized carbon material (ZC600) derived from ZIF-67 assisted polyvinylidene fluoride hollow fiber membrane by a simple anaerobic calcination method at a relative low temperature (600 • C). the obtained carbon material (ZC600) showed a specific capacitance of 652 F g −1 at the current density of 1 A g −1 in three electrode system. After 20,000 cycles, the cycling retention rate was 97.1% at 10 A g −1 . Lei et al. [77] prepared ZIF-67/SiO 2 /RF-M composite material through one-pot method using ZIF-67, TEOS, resorcinol and formaldehyde in alkaline solution. After carbonization and remove of silica, the N-doped porous carbon (Carbon-ZSR-M) was obtained. The obtained Carbon-ZSR showed a specific capacitance of 305 at 1 A g −1 , due to the highly conductive and large specific surface area. We used Equations (S2) and (S3) to calculate the energy and power densities, respectively, of our materials to construct the Ragone plot ( Figure S6

Preparation of Zeolitic Imidazolate Frameworks Containing Co (ZIF-67)
Solution A was formed by dissolving 2-methylimidazole (224 mmol, 18.4 g) in absolute MeOH (15 mL). The solution B was formed from Co(NO 3 ) 2 ·6H 2 O (12.5 mmol, 3.64 g) in absolute MeOH (15 mL). Both solutions were stirred for 25 min at 25 • C. After 20 min, solution A was poured slowly into solution B to form a purple solution, which was kept for 24 h at 25 • C to give a purple solid. This solid was filtered off and washed with MeOH to afford ZIF-67 as a purple powder.

Preparation of MPC
AP-BZ POP was heated in an ampoule under a N 2 atmosphere at a heating rate of 1 • C min -1 up to 500 • C and then this temperature was maintained for 8 h. After cooling to room temperature, the black material was collected to afford the MPC.

Preparation of PCMC
AP-BZ POP/ZIF-67 (0.20 g) was immersed and stirred in acetic acid (30 mL) for 24 h at 25 • C to remove the ZIF-67. The obtained solid was filtered off and dried at 100 • C for 24 h. The brown material was heated at a rate of 1 • C min -1 up to 500 • C and then this temperature was maintained for 8 h under a N 2 atmosphere. After cooling to room temperature, the resulting black material was collected to afford the PCMC (Scheme 2).

Conclusions
We prepared a new bio-based BZ (AP-BZ) through Mannich condensation of apigenin (as the phenol) with 4-bromoaniline and paraformaldehyde. We then used Sonogashira coupling of AP-BZ with P-T to afford a new porous polymer, PA-BZ POP. Finally, we synthesized a spherically shaped PCMC through Sonogashira coupling in the presence of a zeolitic imidazolate framework as a directing template, affording PA-BZ and after etching and pyrolysis processes. Our as-prepared PCMC material exhibited outstanding thermal stability, a high BET surface area (1110 m 2 g -1 ), high CO 2 adsorption (5.40 mmol g -1 at 273 K), excellent capacitance (735 F g -1 ), and capacitance retention of up to 95% after 2000 galvanostatic charge/discharge cycles; these characteristics were superior to those of the corresponding MPC and other porous materials.

Data Availability Statement:
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.